Porous implant materials are understood, for example, as meaning bone substitute materials which are used as implants for the substitution or the reconstitution of bone structures on account of defects after illness- or accident-related surgical interventions. Examples which may be mentioned are molded implant articles such as bone prostheses of many different types, bone connecting elements, for example in the form of intramedullary nails, bone screws and osteosynthesis plates, implant materials for filling spongiosa bone defects or tooth extraction cavities as well for the plastic surgery treatment of contour defects in the jaw/face area.
This term furthermore includes surface-structured implants, such as, for example, dental implants or metal prostheses for the replacement of joints. Furthermore, these are also to be understood as meaning non-woven materials, membranes, fabric, laminates and the like for wound coverings, skin replacement, vascular prostheses or alternatively ligament replacement.
For the healing process, those implant materials which have a high bioactivity are to be regarded as particularly favorable, in that they are taken up in the body and then integrated into it. In the case of bone substitute material, this means that it should soon coalesce firmly and permanently with endogenous tissue, in particular with the bone. DE 41 21 043 describes a bone substitute material which contains, in a porous matrix, one or more polypeptides having the biological action of fibroblast growth factors. Good results are indeed obtained there in the stimulation of bone growth into the porous structure of the implant, but there are also some still unsolved problems. On the one hand, the stability of the peptide growth factors applied in dissolved form can cause problems and on the other hand the biological action cannot be optionally and reproducibly set due to the uncontrolled release. These problems of stability and uncontrolled release are also to be found in the case of other active compounds, such &s, for example, antibiotics, cytostatics or other growth-promoting substances with which the implant material is charged.